5 KAC Bolt Carrier Physicals & 1 LMT Enhanced Bolt Physical

[@CharlesVanNoland]

In my experience running CNC lathes and mills for my late father at his shop I'm not surprised that the carriers that had wider bolt-shoulder bores also had wider *everything-else* on there. The machine runs a few dozen parts (lathe) and begins to warm up and will start to go off of what the G-code is intended to machine. My father had me checking every part to watch for the machine shifting, and inputting tool offsets as things changed to maintain +/- 0.001" tolerances on the parts we'd be running for optics/medical/military jobs that would come in.

[@Wehra96]

at least +/- 1 thou is a fairly trivial tolerance to meet.

[@johngarlick7115]

@@Wehra96 as someone that works as a machinist for the military, and have machined for medical also bores that tend to have alignment, or intended to have other moving parts inside them tend to be sub 1 thousandth tolerance, especially when pertaining to perpendicularity to the base datum, and towards the original post you shouldn’t be running a machine in auto that has not been warmed up properly, causes a lot of premature wear to the machine and wildly varying tolerances

[@Wehra96]

@@johngarlick7115 i worked with hydraulics and parts relating to hydraulic low pressure motors i've worked with tolerances all the way down to +0 -0.003mm, +/-0.00039 inches or +/-0.01mm would be our standard tolerance for stuff meant to fit together while moving. tighter for smaller stuff. our machines were never shut off unless we needed to restart the NC and kept them running for 12-16 hours per day autonomously so a cold machine was never really an issue. We also had a lathe that was used for very high precision large stuff that was shut down over night and we pretty much just let the spindle spin for a few minutes before starting to machine the parts.

[@johngarlick7115]

@@Wehra96 same thing we do bud s500 m3 for about 20-30 mins while the rest of the hydraulics run generally gets you where you need to be as far as everything being consistent, older machines may take a bit longer, or ones with ceramic spindle bearings as they don’t warm up easy on ceramic bearing equipped I have the guys run on the mid range rpm of low gear, then after 20 mins go to the mid range of high gear, and yeah tight tolerances can be a bear but once your there your there as long as you s+f’s are good and don’t chew your tools up. A lot of our important bores are +.0003 -.0000 so I feel you on those tolerances lol

[@johngarlick7115]

@@Wehra96 ever run Siemens 840 controller ? If you use NX to program for them you can actually account for tool wear in a sub cycle based on cycle count, it’s under one of the volumetric comp menus

[@retselyarrh3895]

I like that you had five examples, which was a good batch to indicate quality control. I would like to see you do a physical on a Wilson Combat BCG.

[@Florida_War_Tribe]

So by buddy has had problems with 2 separate BCG’s from Wilson. They did fix it but took them a little while.

[@Jonas-k4w]

I would second that motion.

[@otetechie]

I don’t think some people realize how little one thousandth of an inch difference is. Your average sheet of printer paper is 0.0039 inches, almost 4 times the size.

[@p47rr]

I am extremely happy that I found your channel. Was just about to buy a nickel boron coated bcg. After watching your video on bcg coatings. I settle on a phosphate coated chrome lined bcg for my LR308 build. Couldn’t find a chrome one in stock anywhere. I thought that phosphate was the worst coating. Especially after watching so many reviews that nickel boron was so amazing.

[@gretchindg]

Some dude dropped some coin on his BCGs. 5 KACs...

[@whiskeyactual.]

@@rifleshooterchannel208 It's more likely that he actually does shoot but has so many different rifles in rotation round count's stay pretty low.

[@m118lr]

Rifle Shooter Channel ...yep, EXACTLY what I was thinking. I thought “autopsys” were for dead parts, NOT NEW..?

[@newerest1]

@@m118lr hence why the title says physical and not autopsy

[@ryanpeck3377]

Then dropped even more money on replacing the carrier keys

[@FranciscoDelValle180]

Sucks when others have more money doesn’t it?

[@spadetrump]

This confirms my research that YFS Fasteners in my Bear Creeks Are JuSt aS gUd!

[@vaughnwesterby5162]

Thanks for the LMT bolt autopsy, excellent! I have one coming!

[@sergioarmas6689]

Vaughn Westerby where did you purchase the LMT bolt from?

[@vaughnwesterby5162]

Sergio Armas Brownells but, it’s on backorder. It will take a while to get.

[@IremiaGreece]

Check Titan defense located in Scottsdale, AZ

[@99cobra2881]

Thanks I’m thinking about getting an LMT bolt for my new home defense build. Lowers done, upper is a few paychecks out so having to wait to get one is ok. Loving this channel. I used to think I knew a lot about AR-15s, now I think I didn’t know shit.

[@vaughnwesterby5162]

TheK9COPPER thanks a lot for the tip! I’ve been waiting for a back order at Brownells for a month, l ordered today! Thanks again 👍🏻

[@Evolved272]

We need LMT BCG Physical... Where can those three bore gauges be bought?

[@denbo74]

Would love to see some Colt bcgs

[@GiantPinhead]

Thx Chad. These are very informative.

[@scottsaylors1996]

Rumor has it the man who made a kac bcg rate yellow has never been seen since

[@timturner7609]

It's interesting that the worst screws in the industry are so proud of who they are that they are the only company that stamps their names in the screw

[@hodlwise2470]

He could have just gotten Sionics NP3 BCGs and saved himself some trouble.

[@MLucero91]

I like how they each gauged differently being from the same company. I had the same happen to me with a Geissele. One had the same dimensions as the one you had a video for and the other had a bit looser tolerances.

[@mattnsac]

Different runs can have different tolerances and even start and end of run can and typically do have different tolerances. When you have a CNC running, even taking into consideration of the temperature of the grease in the machine can affect measurments. Its especially the case with cutting tools if you are doing longer runs before checking tolerance; think of a drill running holes over and over, those holes will change the more it cuts and you have to offset or change the tool before it becomes an inssue. KAC has phenomenal QC and this blueprint session proves it out.

[@spookyindeed]

This is why we have tolerances. It''s impossible to produce any parts that are exactly identical.

[@Guero_c7]

i would’ve love to have just seen one sand cutter but holy moly five had my mouth drooling Kac, FN, and HK are my 2a holy trinity lol

[@19840b]

Bro had 5 grand on his table. Thanks gunbroker 😂

[@jdlc-df1ue]

I’m assuming these have all been fired a good amount and if so, I wanna know how he cleans them cause this man has some amazing cleaning talent

[@OddBallPerformance]

Ultrasonic cleaner.

[@racecitypatriot5017]

Yes sonic cleaner. They get ever single bit of dirt off stuff.

[@1badpit100]

Awesome video thank you

[@josephboisvert2030]

Wow….. I subscribed to your channel, great

[@Ldub556]

Will you do a Lwrc bcg autopsy?

[@dogshmog]

I had a KAC sand cutter with an LMT e-bolt that I put together. The LMT bolt was fantastic, as they always are. The SC carrier was not impressive for the cost. Just underwhelming finished machining, this video explains why. The tolerances are just not that great. Do we know if the sr15 bolt is a forged item? I think its reputed strength might be more related to material than the rounded lug design.

[@justsnuggle]

9:00 bolt manufacturer nugget of wisdom

[@ronslusser4233]

Where did you get all your gunsmithing gauging tools from?

[@m118lr]

I think some might have come from Pacific Tool also..saw it in another vid BUT STILL not sure which came from WHERE

[@kochj0713]

You should start a company where you order in a lot of these BCG’s, and then sell them varying on the physicals!

[@trolli0]

I just need two of these please

[@korvenburns1135]

Have you ever seen a Sharps bolt brake

[@Steve_643]

This is why KAC cost so much it’s quality made!!! I’ve never got the opportunity to shoot a KAC gun but I hope to own one some day!!!!

[@otetechie]

Where do you live?

[@choke666]

In your opinion what is thee best, or some of the best carrier assemblies? AR-15 or M16. I love your videos! My new addiction for sure!

[@donnieclark3862]

Wish I knew where to get your testing tools

[@walt3r88]

The more bcg videos I watch, the less confidence I have in any of them haha. With that said, the 3 solgw’s I have run great for me. We’ll see if the two AO’s do well.

[@Justin-zw1hx]

Can you do JP BCG? Thanks!

[@elitetrader5468]

I didn't know the fat wrench works both ways!

[@FandCCD]

Do you make or purchase your gauges?

[@ed0c]

that "enhanced bolt" is $389 by itself! that is insane.

[@bap2139]

so did you have to re-key and re-stake the dude's KAC carrier's?

[@goinhot9133]

Yes he stated and showed he was replacing the keys

[@Cooldibs]

Have you ever seen a bcm bolt fail? If so, what exactly broke on it?

[@Jonas-k4w]

What's the name of the second bolt that's mentioned on 9:00 minute? Does anyone know?

[@skullofserpent5727]

Lmt enhanced bolt?

[@seanwhite304]

My go too BCG when I'm not running suppressed is this combo . KAC Sand Cutter BCG with LMT Enhanced Bolt. I've never heard of anyone breaking LMT Bolt either . I believe Crane was unsuccessful in trying to break one.

[@jonengelbird7051]

What combo do u run when suppressed?

[@seanwhite304]

@@jonengelbird7051 Depends. Usually I'm running Springco Blue Spring with Colt H2 Buffer. Sometimes I'll run Springco Blue Spring , Car Buffer and BRT Tuned 0.73 gas tube . I run 13.X Mid Lengths. Also quite a fee variables that depend on what combo or setup I use . If using Gassy Can than might wanna go with BRT Tuned Gas Tube . Flow thru type can you'd might wanna run Springco Blue with H Buffer . If using A5 System then Springco Green with A5H2 or A5H3 . The way it was explained to me is A5H2 Buffer is equivalent to Standard Car H buffer and A5H3 ould be same as Car H2 Buffer. For the most part Springco Blue Spring with Colt H2 buffer is what I use . Weaker 223 55g FMJ ammo might Short stroke when using this combo non suppressed . For Carbine Length Gas system I usually run Springco Red with Colt H2 because the action is way more violent .

[@MannyScoot]

Who makes the best recommended 7.62x39 in your opinion ?... Thanks for your lessons !!!

[@madeintexas1213]

AK47...

[@YukarisGearReviews]

@@madeintexas1213 he was asking about a bolt carrier group.

[@sawyerprince5567]

@@YukarisGearReviews I think he was saying an AR47 is stupid. For the most part I agree with him. CMMG prolly makes the best components for AR47s. There are no good mags out there for them. No Duramag and pro mag are not good. I’d just go with an AK. Proven for that round.

[@DACFalloutRanger]

Holy shit it must be Christmas!

[@trixi8520]

I'm in heaven with all of these physicals.

[@99cobra2881]

I know right! I’ve torn my bcgs all down and checked them with what I could but not entirely due to not having all the go no go gauges. Great content here and it’s made me laugh when thinking about some of the other review and comparison videos I’ve watched before that really didn’t check or compare anything!

[@KaneGregory]

Can you run a KAC BCG in other rifles???🤯🔫👍🏽

[@StefanSu91]

Only the carrier, not the bolt.

[@colbyc.6698]

Is there a way to demagnetize without a machine

[@chaskaryan7228]

This is my extractor tool Obviously

[@patricks792]

What size rod are you using to guage the gas key alignment?

[@jeffreyfields3771]

Would you do a smith and wesson bcg physical or link me to one please

[@12345678971926]

You basically have a lot of money on your table

[@kylesharpe9355]

Can you recommend some of the best Bolt carrier groups? FCD?

[@nbates9893]

Two examples of quality companies are in this video.

[@loganyoung2408]

Hard to beat FCD

[@madeintexas1213]

Sionics, Forward control designes, BCM, Geissele, Daniel defense, Lantac, SOLGW, LMT, KAC

[@AstraZero7]

@@madeintexas1213 basically Microbest bcgs are very good

[@davidkish9026]

What would be the go nogo pin gauge size for a AR15 5.56

[@skullfan33]

where can i find these gauges?!

[@itsthorondil7608]

Excuse my ignorance. What is bad about having magnetism in some of the parts? Extra resistance in motion due to eddy currents?

[@TheChad138]

Not an expert myself so take what I say with a grain of salt, but from what I can tell is these parts are made of stainless steel, so you shouldn’t see anything magnetic.

[@itsthorondil7608]

@@TheChad138 ah, so hints of magnetism would point to low quality/cheap, unsafe material like basic iron?

[@TheChad138]

@@itsthorondil7608 just watched another video of his and he said it’s not a big deal if using brass cased ammo, but if you use steel or bimetallic cased ammo it would leave shavings and could mess things up.

[@Andrew85or]

@@TheChad138 Some stainless like 18-18/304 do have slight magnetic properties while others, like 316, do not. They also have different resistances to chemicals. 304 will rust when introduced to chlorine while 316 doesn't. Not sure what barrels are typically made of off the top of my head. I just sell fasteners, so have some knowledge.

[@cajunmaker6917]

my OCD got a woody

[@DeusExMachina_TX]

Hey Chad, How big are the differences in those gauges when you check the "three bore" dimensions? Thanks for making these videos!

[@LeCafeRacer]

I think he said the gauges had .001" in between them. Your hair is .004". I'm not sure the efficacy of checking those diameters in .001" increments. At that point you are LITERALLY splitting hairs. Maybe you would want to know if its .005" out of spec. A clearance fit where two parts can freely move typically has at least .002" to .003" unless you have perfectly ground surfaces. Lower than that and AIR has a hard time even getting past.. Im not sure what you learn discovering that your carrier is .001" oversized. EDIT: Id be hard pressed to find many if any features on the original AR drawings has a +/- .001" tolerance. I love the videos, but I think some of this stuff is overboard. You could measure most this stuff with telescoping gauges and a pair of calipers; spending a lot less; and having to store dozens fewer amount of tools. Those precision ground gauges are ideally used when checking production quantities where you can't take the time to measure it or have people that don't know the measurement; they are just paid to stick the gauge in the hole and put it aside.

[@rottdogsparky]

@@LeCafeRacer So I would be interested in the tools that you are talking about, simply because the issue with the tools to measure the exact tolerances are expensive? Don't they require annual certification? Training? Great feedback!

[@bf4chode2]

Back in those days +/-.001 would be a cake walk. As a machinist for over a decade, I have come across many prints from the 60’s and 70’s that had tolerances of +/-.00025”.

[@chadporter55]

Will the lmt enchanced bolt work in a kac mod 2 with the e3 design?

[@TheSarahnov16]

Chad how you liking the AO Precision Bcg thinking of getting one they decent for the money any better than Toolcraft thanks

[@itsfree2639]

AO has DOD contracts. They are g2g. Geissele bcg (not enhanced) are just rebranded AO precision bcg.

[@Wraith35]

For what that bolt cost you should get a 2nd date. lol

[@recceshoe6911]

Does the knights carrier have milspec cam pin path geometry?

[@jonathannoebel6457]

Could someone please tell me. Is Knights Armaments as good as people say they are cause you hear yes and no. Or is it because they are expensive?

[@doktorfaustus]

Both. As a rule they make excellent quality products, but they charge a huge premium for their name.

[@hm096]

They’re one of the best manufacturers for AR15/AR10 parts. The quality of their products is insane.

[@iwillnotcomply007]

What is the relevance of the magnetic check?

[@jaeger1447]

Steel-case ammo can apparently leave metallic particulates that accumulate over time in the bolt or upper receiver. Magnetized parts can pick up and retain these in critical areas with limited clearances - I believe the area of particular concern is the firing pin channel.

[@iwillnotcomply007]

@@jaeger1447 interesting

[@AslamKhan-hk3tx]

Seal in Bangladesh

[@concernedpatriot.2221]

5 knights armament BCG and ALL have different specs. Keep in mind these BCG are about 4 times for expensive than other BCG’s. What a joke ! Nothing but a name. BTW. If KAC are so good, why does the owner feel the need to have the gas key replaced. 🤦🏻‍♂️

[@Invitingsauce]

I’ve never seen a bolt with sheared lugs. Only broken at the cam hole. Seems a properly gassed gun wouldn’t break quality parts until very far in the future. Like a 20k round count or something more

[@SchooloftheAmericanRifle]

I have about a dozen broken bolts in my shop.

[@whiskeyactual.]

The KAC BC physicals are boring as expected LOL. Solid equipment here

[@Godscaliber1911]

All I see from kac is a bunch of inconsistency

[@skm9420]

500 bucks they better be perfect.

[@giddy6196]

The differences between cheap and expensive ARs is the cost lol, think about that for a second.

[@josephboisvert2030]

Wow….. I subscribed to your channel, great

[@josephboisvert2030]

Wow….. I subscribed to your channel, great